Semiconductors are extremely important articles of commerce required in various industries, and typically semiconductor chips are manufactured by the technology which comprises slicing a silicon single crystal to prepare a silicon wafer having a predetermined thickness and constructing various circuits and other components on said wafer.
In the above process for manufacturing a semiconductor chip, various semiconductor production implements each based on a ceramic board, such as the electrostatic chuck, hot plate, wafer prober and susceptor, are used on many occasions.
Regarding such implements for semiconductor manufacture apparatuses, the ceramic boards for use in these applications are described in JP Kokoku 2587289 and Japanese Kokai Publication Hei-10-72260, for instance.
The ceramic boards disclosed in the above patent literature and other publications are invariably available only within the size range of not over about 6 inches (150 mm) in diameter and not less than 8 mm in thickness.
However, the recent trend toward increase in the size of a silicon wafer has led to a demand for ceramic boards as large as 8 inches or more in diameter.
Meanwhile, in the process for manufacturing silicon wafers, heating procedures require the use of a heater having a heating element embedded in a ceramic substrate and for achieving an improved temperature response or follow-up efficiency through a reduction in heat capacity, the thickness of the ceramic board must be reduced to less than 8 mm.
On the other hand, there has been disclosed a ceramic board having a wafer-mounting surface controlled to a roughness value of not more than Rmax=2 μm (Japanese Kokai Publication Hei-7-280462).
However, the manufacture of a hot plate, an electrostatic chuck or the like using such a large and thin ceramic board was found to involve various problems, for example the creation of a temperature gradient in the silicon wafer placed thereon and consequent destruction of the wafer by thermal shock or the failure to generate a sufficient chucking force despite the reduced surface roughness and the consequent non-uniformity of wafer temperature.